Process of sizing paper



'stituent consists principally of petrolatum.

Patented Jan. 19, 1932 HERBERT P, PEARSON, OF NEW YORK, N. Y., ASSIG-NOR TO STANCO, INCORPORATED, A

' CORPORATION OF DELAWARE PROCESS OF SIZING PAPER No Drawing.

This invention relates to an improved size and more particularly to a size useful in the manufacture of water resistant paper. It also relates to a method of manufacturing paper and more particularly water resistant paper.

An-object of the invention is to produce a paper of superior water resistant properties utilizing the water repellent property of petrolatum.

Another object is to produce a low priced size which will impart a very high degree of water resisting quality together with pliability to the paper.

Other objects will be apparent from the following description.

Heretofore it has been proposed to incorporate minor proportions of petrolatum with a main body of other sizing agents such as parafiin wax. For example, it has been proposed to emulsify 810 lbs. of paraflin, 112 lbs. of stearic acid and 125 lbs. of petrolatum with 100 gallons of waterto obtain a water proofing composition, using as emulsifying agent the reaction products of 112 parts of fatty acid and 27 parts of soda ash. So far as I am aware there are no sizes known commercially in which the water-resisting con- I have discovered that paper of excellent water-resistant quality can be prepared by incorporating with the pulp prior to its formation into paper an aqueous emulsion of petrolatum. One of several methods of emulsification may be used for preparing such an emulsion. Good results have been obtained for instance by using an emulsifying agent such as aqueous solution'of silicate of soda in the presence of small proportions of a protective colloid such as glue and then pre-setting with a precipitant such as alum.

The emulsion is incorporated with the pulp before its formation into sheet paper either in the beater, or preferably, the emulsion is added to the mixture of acidified water and pulp on the screens. If the sizing emulsion is added at the beater care must be taken that the temperature of the pulp in the beater be kept below the melting point of the petrolatum used. For this reason this water Serial No. 403,916.

resisting size is preferably added at the screens. However, when petrolatum having a melting point higher than 150 F. is used, such as the one obtainable from Talang Akar crude which has a melting point of 170 F then the emulsion may be added in the beater engine.

The following example will serve to illustrate the process. 100 lbs. of Ranger petrolatum having a melting point of 135 F. approx mately, 2 lbs. of glue, 18 lbs. of sodium silicate dissolved in 160 lbs. of water and 10 lbs. of alum dissolved in about 30 lbs. of Water were thoroughly agitated in a mixer at a temperature of 170 F. until completely emulsified. The petrolatum was obtamed from Ranger crude, had M. P. 135 F. and contained about 5070% of wax and 50-30% of heavy oil of cylinder stock grade. A small amount e. g. 2 lbs. of Japan or Montan wax may also be used in the emulsion, if desired.

The method of preparing the emulsion, however, constitutes no part of the present invention. Other methods of emulsification may be used. For example, the petrolatum, wlth or without the addition of other sizing agents, may be emulsified in a colloid mill in the presence of a soap solution as emulsifying agent.

The emulsion of the above example may be further diluted with 56 times its weight of water and added to the pulp and water mixture as it passes through the screens. If thepulp has an acid reaction, no further precipitant is necessary; however, in most cases it is preferable to add some alum to the diluting water before mixing with the pulp i and the emulsion to insure the right degree of acidity of the pulp.

It is known to those skilled in the art that petrolatum contains wax which is very difficult to separate from the oil in the .petrolatum. For this reason the petrolatum wax is usually called amorphous wax in practice, although this wax is actually present in the form of very fine crysta s. In contradistinction to this wax the usual paraffin wax of commerce consists of wax particles crystallized in much larger crystals.

In a modification of my process I may add paraflin wax, rosin or other sizing agent, to the petrolatum before preparing the emulsion. Usually, however, it is not advantageous from economic standpoint to add more than 20% of paraflin wax, rosin, etc.; in some cases a mixture containing as high as 80% of added paraflin Wax, rosin or other sizing agent, with 20% of petrolatum may be used in preparing the water-proof emulsion. Small amounts of a protective colloid such as glue are used in the emulsion with advantage and small amounts of Japan or Montan wax may also be added as already stated.

A feature of my invention is that the paper manufactured with my petrolatum base size has better water-resistant quality than the one prepared with other sizes. rolatum in the final paper product will render the paper water-resistant, but the amount of petrolatum may be increased to 35%.

Unless a highly purified petrolatum is used the petrolatum size may impart some color to the paper. If so, it should be mainly used in the manufacture of papers which are not required to have a perfectly white color. My size and process are therefore especially applicable to the manufacture of paper board, food containers, wrapping papers, etc. Since 1% of pet-- which comprises incorporating into paper pulp prior to its formation into paper sheet an aqueous emulsion comprising a mixture of at least 20% of petrolatum with not over 80% of added wax, the reaction product of aqueous sodium silicate solution and alum, and forming paper sheet from said pulp.

4. The process of manufacturing paper,

vwhich comprises incorporating into paper the average market price of the petrolatum is less than half of the price of the paraflin wax which has heretofore been used in sizes for preparing water-resistant paper, the economic advantages of my process are obvious.

Various modifications of my process will be obvious to those skilled in the art. For instance, the petrolatum base size of the present invention may be used in combination with other sizes such as a usual rosin size. I may add the rosin size in the heater and the petrolatum base size at the screens.

Another modification consists in sizing the paper, after its formation into paper sheet, at the calenders with the petrolatum base size.

In the following claims the expression solid petrolatum is used to designate a petrolatum which is solid at ordinary room temperature, in contradistinction to liquid petrolatum.

Having thus described my invention and the method by which it may be carried out what I claim is 1. The process of manufacturing paper, which comprises incorporating in paper pulp prior to its formation into paper sheet, an emulsion of solid petrolatum, and forming paper from said pulp.

2. The process of manufacturing paper which comprises incorporating in paper pulp prior to its formation into paper sheet a preset emulsion of solid petrolatum and forming paper from said pulp.

3. The process of manufacturing paper,

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